Linewidth factors contributing

With the above Rabi frequencies, calculated using the experimentally measured laser power W, a linewidth of 1.7 MHz is calculated. Several other factors contributing to the observed linewidth of 4 MHz, are listed in Table II. Here Vq == /2kT/M is the thermal... 

This transport mechanism has been further studied on oriented systems, polymer electrolyte materials that had been mechanically or magnetically oriented in a certain direction. NMR studies have revealed important facts about lithium-polymer complexes within these anisotropic systems. It was established that the re-ordering induced by the stretching extends down to the immediate environment of the cation, as evidenced by obtained angular-dependent linewidths. At the same time the diffusion coefficients were shown to increase along the stretched direction indicating that other factors contribute to the ion-transport mechanism, such as the alignment of the structural units of the polymer chains. Additional evidence for this was... 

After the signal emerges from the lock-m amplifier it still contains a considerable amount of noise. Most of the noise contributions to the signal can be eliminated by passing the signal tlirough a low-pass filter. The filter tune constant is a measure of the cutoff frequency of the filter. If accurate linewidth and g-factor... 

Equation (5) shows that the contribution to the homogeneous linewidth from the excitation of the low-frequency mode will be exponentially activated. The right-hand side of Equation (5) is consistent with Equation (4) which was used to fit the data. The factor multiplying the exponential is the constant a2 in Equation (4). This term dominates the temperature dependence at high temperature. 

The contribution of Ti to the total linewidth T (FWHM) is highly variable. Table 1 shows the contributions for the molecules studied here. The lifetime is a significant factor in pure CH3I, a small correction in CH3CN, and negligible in ethanol. The lifetime has not been measured in toluene, but a similar frequency mode in benzene has a long lifetime (98). 

This relaxation time is very important as it is associated to the natural linewidth . However the time constant T2 cannot be directly quantified, because there are other factors which also contribute to the dephasing process. These factors are experimental factors and are related to the inhomogeneity of the Bo field in the sample. As different molecules in the sample experience slightly different Bo fields, their precession frequency (and resonance frequency, vo) is slightly different, thus the dephasing is faster, T2 becomes shorter, and the actual line in the spectrum is artificially broadened. 

According to the Bohr model of the atom, atomic absorption and emission linewidths should be infinitely narrow, because there is only one discrete value for the energy of a given transition. However, there are several factors that contribute to line broadening. The natural width of a spectral line is determined by the Heisenberg uncertainty principle and the lifetime of the excited state. Most excited states have lifetimes of s,... 

In parallel with these experimental studies of PL for SQD suspensions, the role of the observed linewidth broadening has been examined. In particular, the linewidth broadening due to acoustic-phonon-assisted transitions is expected [1] to contribute to satellite lines in PL spectra that are downshifted by the acoustic phonon energies. Within the elastic continuum approach [6], the phonon mode frequencies sensitive to the boundary conditions at the SQD surface were calculated. The lowest-order spherical acoustic mode frequency for CdS for different matrix materials differ by as much as a factor of three for a given SQD radius. 

Doppler broadening is not an important factor in the lower MMW frequency region at ambient temperatures or below. At higher MMW frequencies its contribution to the overall linewidth could, however, become significant. Its effect can be readily demonstrated by recalling that the relative frequency shift in the spectral absorption due to the velocity of the molecule v with respect to the direction of the MMW radiation is ... 

The linewidth of resonance peaks (width measured at half the height of resonance peak), AH, depends on a variety of factors. Anisotropy field effects can be expressed in terms of a damping constant leading to a contribution to AH. If the dc field is not strong enough to saturate the... 

The existence of a bimodal linewidth distribution may be attributed to several factors. When a polymer is large, interference between segments of the same chain will give rise to an intramolecular scattering contribution to the linewidth. We have ruled out this possibility since K has a maximum value of 1.2 and is often much less than one in our experiments. Thus, our experiments cannot observe the contributions due to internal motions and they amount to, at most, one to two percent of the total scattered intensity.(lO) We have also made other studies whereby a second faster peak can be attributed to a pseudo-gel motion in semidilute solutions (l ). This explanation is unreasonable because the concentrations of our solutions are very small. We should not have reached the semidilute regime. 

The relaxation rates of a quadrupolar nucleus are dictated by two new factors not previously considered. The first is the magnitude of the quadrupole moment itself (Table 2.3). Larger values contribute to more efficient spin relaxation and hence broader linewidths, whereas smaller values typically produce sharper lines. Thus, those nuclei with smaller quadrupole moments are usually more favoured for NMR observation. As before, for the mechanism to be effective, molecular tumbling must occur at an appropriate... 

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